Semiconductor light emitting chips (hereinafter referred to as "LED chips") generating blue type light are conventionally manufactured in the following manner. As shown in FIG. 2, there are sequentially formed, through epitaxial growth onto a sapphire substrate 21, an n-type layer (cladding layer) 23 of e.g. n-type GaN, an active layer (light emitting layer) 24 of e.g. InGaN based compound semiconductor (wherein the ratio of In and Ga may be varied as it similarly applies hereinafter) which is a material which band gap energy is smaller than that of the cladding layer and which determines the light 25 emitting wavelength, and a p-type layer (cladding layer) of p-type GaN. Annealing treatment for activating a p-type layer can be performed i atmosphere of vacuum condition, nitrogen gas, inert gas, or the like. A p-side electrode 28 is formed onto a surface of the substrate with a current diffusion layer 27 interposed between, and a part of the laminated semiconductor layers are etched so that an n-side electrode 29 is formed on the exposed surface of the n-type layer 23. Thereafter, by dividing the wafer into individual chips, LED chips as shown in FIG. 2 can be obtained.
As mentioned above, in conventional methods of manufacturing semiconductor light emitting device employing gallium nitride based compound semiconductor, annealing treatment is performed after laminating the semiconductor layers in order to activate the p-type layer. This annealing is performed, as mentioned, in a vacuum condition or in an inert gas atmosphere. Such treatment is taken because surfaces of gallium nitride based compound semiconductors are slightly oxidized in case of undergoing heat treatment at approximately 600.degree. C. at an oxygen atmosphere though it presents stability against corrosion, so that adhesion with a current diffusion layer that is to be formed thereon or electrical characteristics such as electrical conductivity are degraded.
However, it is conventionally required to perform annealing treatment at high temperature ranging from 500 to 800.degree. C. and for a long time of approximately 1 to 2 hours otherwise no sufficient activation can be achieved and the electrical resistance of the p-type layer can not be sufficiently decreased.